File:Gaussian Function.png
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Gaussian_Function.png (320 × 177 pixels, file size: 6 KB, MIME type: image/png)
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Summary
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| Description |
English: The famous Bell Curve. |
| Date | |
| Source | Own work |
| Author | Philip Rideout |
Licensing
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I, the copyright holder of this work, hereby publish it under the following license:
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
Source Code
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Uses C99 and Cairo.
#include <cairo.h>
#include <math.h>
#include <stdio.h>
int main()
{
double width = 320, height = 240;
double f, delta = 0.125;
cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
cairo_t *crc = cairo_create(surface);
cairo_text_extents_t extents;
cairo_font_options_t* font;
// Set up font (face is second field in 'xlsfonts'; first field is foundry)
font = cairo_font_options_create();
cairo_font_options_set_antialias(font, CAIRO_ANTIALIAS_SUBPIXEL);
cairo_set_font_options(crc, font);
cairo_select_font_face(crc, "nimbus sans l", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
cairo_set_font_size(crc, 16);
cairo_font_options_destroy(font);
// Background
cairo_rectangle(crc, 0, 0, width, height);
cairo_set_source_rgb(crc, 1, 1, 1);
cairo_fill(crc);
// Fill
cairo_move_to(crc, 0, 220);
for (f = -4; f < 4; f += delta)
{
double v = exp(-f * f / 2) / sqrt(2 * M_PI);
cairo_line_to(crc, width * (f + 4) / 8, 220 - v * height);
}
cairo_close_path(crc);
cairo_set_source_rgb(crc, 122 / 255.0, 143 / 255.0, 248 / 255.0);
cairo_fill(crc);
// Graph
cairo_move_to(crc, 0, 220);
for (f = -4; f < 4; f += delta)
{
double v = exp(-f * f / 2) / sqrt(2 * M_PI);
cairo_line_to(crc, width * (f + 4) / 8, 220 - v * height);
}
cairo_set_line_width(crc, 2);
cairo_set_source_rgb(crc, 7 / 255.0, 16 / 255.0, 141 / 255.0);
cairo_stroke(crc);
// Vertical Axis
cairo_set_source_rgb(crc, 0, 0, 0);
cairo_move_to(crc, width / 2, 0);
cairo_line_to(crc, width / 2, height);
cairo_stroke(crc);
// Horizontal Axis
cairo_move_to(crc, 0, 220);
cairo_line_to(crc, width, 220);
cairo_stroke(crc);
// Horizontal Ticks
cairo_set_line_width(crc, 1);
for (f = -4; f < 4; f++)
{
cairo_move_to(crc, width * (f + 4) / 8, 220 - 5);
cairo_line_to(crc, width * (f + 4) / 8, 220 + 5);
cairo_stroke(crc);
if (f > -4 && f != 0 && f < +4)
{
char str[] = "+3";
if (f > 0)
sprintf(str, "%d", (int) f);
else
sprintf(str, "%d", (int) f);
cairo_text_extents(crc, str, &extents);
cairo_move_to(crc, width * (f + 4) / 8 - extents.width / 2, 220 + 7 + extents.height);
cairo_show_text(crc, str);
}
}
// Vertical Ticks
for (f = +1; f >= -1; f -= 0.1)
{
cairo_move_to(crc, width / 2 - 5, 220 + f * height);
cairo_line_to(crc, width / 2 + 5, 220 + f * height);
cairo_stroke(crc);
}
cairo_text_extents(crc, "0.5", &extents);
cairo_move_to(crc, width / 2 + 7, 220 - 0.5 * height + extents.height / 2);
cairo_show_text(crc, "0.5");
cairo_surface_write_to_png(surface, "gauss.png");
return 0;
}
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 04:59, 16 April 2012 | | 320 × 177 (6 KB) | Philiprideout (talk | contribs) |
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